Showing papers by "Oswald H. W. Siegmund published in 1997"
15 Oct 1997
TL;DR: The microchannel plate, delay line, detectors developed for the far ultraviolet spectroscopic explorer mission to be launched in 1998 are described in this paper, where two FUSE detectors have a large format (approximately equals 184 mm by 10 mm split into two 88.5 × 10 mm segments), with high spatial resolution (less than 20 micrometer by 50 micrometers FWHM, greater than 9000 by 200 resolution elements) and good linearity, high image stability, and counting rates in excess of 4 by 104 events sec-1.
Abstract: The microchannel plate, delay line, detectors developed for the far ultraviolet spectroscopic explorer mission to be launched in 1998 are described. The two FUSE detectors have a large format (approximately equals 184 mm by 10 mm split into two 88.5 by 10 mm segments), with high spatial resolution (less than 20 micrometers by 50 micrometers FWHM, greater than 9000 by 200 resolution elements) and good linearity (plus or minus 25 micrometers), high image stability, and counting rates in excess of 4 by 104 events sec-1. KBr opaque photocathodes have been employed to provide quantum detection efficiencies of 30 - 40% in the 900 - 1200 angstrom range. Microchannel plates with 10 micrometer pores and an 80:1 pore length to diameter ratio, with a 95 mm by 20 mm format have been used in a Z stack configuration to provide the photon amplification (gain approximately equals 2 by 107). These show narrow pulse height distributions (less than 35% FWHM) even with uniform flood illumination, and good background levels (less than 0.3 event cm-2sec-1). Flat field images are demanded by the microchannel plate multifiber boundary fixed pattern noise and are stable.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
62 citations
TL;DR: In this paper, a 3 by 3 centroiding system was developed for a photon counting intensified CCD where single MCP events due to photon or particle detections are centroided to CCD subpixel accuracy.
Abstract: We present the results of a development of a photon counting intensified CCD where single MCP events due to photon or particle detections are centroided to CCD subpixel accuracy. In this mode, we have ben able to resolve individual MCP 6 micron pores indicating the ultimate resolution of this device is limited by the microchannel pore spacing and not the readout technique. Using an EEV camera with a 512 by 512 CCD and a frame rate of 60 Hz, we achieve a global counting rate of 50,000 cts. per sec. The key to achieving rates this high for a 3 by 3 centroiding system is the identification of the pixel address of the event location in hardware using a dedicated convolution DSP and comparators which pass only valid events for the centroid calculation to downstream processors. We will also discuss the centroiding algorithm development and optimization and the corrections that must be applied for quantized and truncated sampling of the event charge distribution. At very high event rates the device may also be operated in analog mode with resolution.
17 citations
15 Oct 1997
TL;DR: In this paper, a detailed study of the basic operation of a relatively new type of electron multipliers, microsphere plates (MSPs), has been reported, and measurements of bare MSP quantum efficiency at incoming radiation wavelength range of 250 - 1450 angstrom were presented.
Abstract: The principles and a detailed study of the basic operation of a relatively new type of electron multipliers -- microsphere plates (MSPs) has been reported recently. In this paper we extend these studied by presenting measurements of bare MSP quantum efficiency at incoming radiation wavelength range of 250 - 1450 angstrom. MSP efficiency appeared to be by an order of magnitude lower than that of bare microchannel plates (MCPs), having maximum of about 1% at 350 - 900 angstroms. We also extend the previous investigation of angular dependence of MSP gain and detection efficiency to an angular range of 90 plus or minus 40 degrees, when no gain depression was observed, while detection efficiency varied only by approximately 7%. The spatial charge cloud distribution of microsphere plates was measured with the help of a phosphor screen, showing that the dependence is quasi-symmetrical although featuring granular formations caused by the intrinsic structure of the plate. We also present a detailed study of combined MCP/MSP stack operation, suggested earlier by L. B. C. Worth et al. The gain of the stack was measured to be relatively high (108) with pulse height distribution FWHM values as low as approximately 62% and dark noise count rates less than 0.1 counts cm-2s-1, limited by the front MCP. The spatial resolution reached the best value of about 80 micrometers with a 250 micrometer gap between the plates and an accelerating bias in the gap of 50 V. The counting rate capabilities of this hybrid stack are much better (no gain drop was observed at count rates of 3.3 (DOT) 105 counts cm-2s-1) than those of purely MSP detector (103 counts cm-2s-1).© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
2 citations